JP2502691B2 - Actual steering angle control device for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a vehicle actual vehicle which controls a steering angle of at least one of a front wheel and a rear wheel so as to obtain a vehicle dynamic characteristic that a driver can easily perform steering control during steering. The present invention relates to a steering angle control device.

(Prior Art) Conventionally, as a vehicle actual steering angle control device, for example,
The device described in Japanese Patent Publication No. 62-241769 is known.

The above-mentioned conventional device is a steering angle detecting means, a vehicle speed detecting means, and an actual steering angle calculating section which inputs signals from the both detecting means and calculates at least one actual steering angle target value of front wheels or rear wheels, The actual steering angle control unit controls the steering angle of at least one of the front wheels and the rear wheels corresponding to the steering angle calculation unit.

The actual steering angle calculation unit has a reference model that models the desired dynamic characteristics and an estimated model that models the dynamic characteristics of the vehicle. The actual steering angle calculation unit uses the reference model, the steering angle, and the vehicle speed. The actual steering angle target value is calculated so as to obtain a response in which the vehicle motion estimation value based on the estimation model matches or follows the vehicle motion target value set based on the above.

(Problems to be Solved by the Invention) However, in such a conventional vehicle actual steering angle control device, the transfer characteristic of a pre-estimated model is substantially the same as the transfer characteristic of the vehicle to be controlled. If there is no problem, the transfer characteristic (solid line) of the estimated model given in advance does not match the transfer characteristic (dotted line) of the vehicle to be controlled, as shown in FIG. As shown in the figure, a reference model (solid line) that gives the target value of the vehicle motion,
There is a problem that the error (hatched portion) from the actual vehicle output value (dotted line) appearing as a control result becomes large, the vehicle deviates from the motion target value of the reference model, and desired vehicle dynamic characteristics cannot be obtained.

Therefore, as a method of solving this problem, that is, one method of matching the transfer characteristics of the estimation model and the transfer characteristics of the vehicle, there is a method of increasing the order of the estimation model.

However, in this case, there are problems described below.

As the order increases, the calculation becomes complicated, the load on the computer used for control increases, and the calculation step (control cycle) cannot be made sufficiently small.

Even if the order of the estimation model is increased, if the parameters of the estimation model change due to rainfall or changes in the road surface friction coefficient, the transfer characteristics of the estimation model and the transfer characteristics of the vehicle also differ.

The present invention has been made in view of the above-mentioned problems, and even if there is a difference between the transfer characteristics of the estimation model and the transfer characteristics of the vehicle, the calculation load is small and is not affected by changes in the running situation. Therefore, it is an object to develop a vehicle actual steering angle control device capable of obtaining a desired vehicle dynamic characteristic that matches or follows the motion target value of the reference model.

(Means for Solving the Problems) In order to solve the above problems, in the vehicle actual steering angle control device of the present invention, the estimation model is used for the control error due to the difference between the transmission characteristics of the estimation model and the transmission characteristics of the vehicle. The means for feeding back the difference between the estimated vehicle output value and the actual vehicle output value obtained by detection to the actual steering angle target value.

That is, as shown in the claim correspondence diagram of FIG. 1, the steering angle detecting means a, the vehicle speed detecting means b, and the both detecting means a and b.
The actual steering angle calculation unit c for calculating the actual steering angle target value δ ₀ of at least one of the front wheels and the rear wheels by inputting the signal from the front wheel and at least one of the front wheels and the rear wheels corresponding to the actual steering angle calculation unit c. And an actual steering angle control section d for controlling the actual steering angle δ of
The actual steering angle calculation unit c has a reference model e that models desired dynamic characteristics and an estimated model f that models dynamic characteristics of the own vehicle, and based on the reference model e, the steering angle θ, and the vehicle speed V. In the vehicle actual steering angle control device, the actual steering angle target value δ ₀ is calculated so as to obtain a response in which the estimated vehicle motion value of the estimation model matches or follows the set vehicle motion target value. The vehicle output actual value detection means g for detecting the vehicle output actual value M, which is the actual value of the vehicle motion corresponding to the above, is provided, and the vehicle is provided between the actual steering angle calculation unit c and the actual steering angle control unit d. An actual steering angle correction value calculation unit h for calculating an actual steering angle correction value δ ₁ by comparing the actual vehicle output value M from the actual output value detection means g and the estimated vehicle output value from the estimation model f, steering angle correction value [delta] ₁ and the actual steering angle target value [delta] ₀ from the actual steering angle calculating section c Thus the final output calculated the final actual steering angle target value [delta] ^* in the actual steering angle control unit d actual steering angle calculator i
Is provided as a means.

The vehicle motion value and the vehicle output value refer to a vehicle yaw rate, a vehicle lateral acceleration, a combined value of a yaw rate and a lateral acceleration, and the like.

In addition, the actual steering angle correction value calculation unit h and the final actual steering angle calculation unit i are as follows: δ ^* = δ ₀ + δ ₁ = δ ₀ + K (−M) δ ^* ; final actual steering angle target value δ ₀ ; Angle target value δ ₁ ; Actual steering angle correction value K; Gain; Vehicle output estimated value M; Vehicle output actual value This is a part for calculating the final actual steering angle target value δ ^* by a relational expression.

(Operation) When the transfer characteristic of the estimated model given in advance does not match the transfer characteristic of the vehicle to be controlled, in the rear wheel steering angle correction value calculation section h, the vehicle output actual value detecting means g detects the vehicle. The actual steering angle correction value δ ₁ is calculated by comparing the actual output value M with the estimated vehicle output value from the estimation model f, and
In the final actual steering angle calculation unit i, the final actual steering angle target value δ ^* is calculated by the actual steering angle correction value δ ₁ and the actual steering angle target value δ ₀ from the actual steering angle calculation unit c, and the final actual steering angle is calculated. The target angle value δ ^* is output to the actual steering angle control unit d.

That is, the actual vehicle output value M that is the control result is fed back, and the rear wheel steering angle target value δ _R is corrected so that the actual vehicle output value M matches the estimated vehicle output value.

Therefore, even if there is a difference between the transfer characteristics of the estimation model f and the transfer characteristics of the vehicle, the calculation load is small and the movement target value of the reference model e is not affected by the change in the running condition, and it is desired to match or follow the motion target value. The vehicle dynamic characteristics can be obtained.

(Example) Hereinafter, the Example of this invention is described based on drawing.

In this embodiment, a desired yaw rate response model (reference model) is set, and a rear wheel steering angle control device for a vehicle by yaw rate model adaptation control that gives a steering angle of a rear wheel so that the response of the vehicle coincides therewith. It is.

 First, the configuration will be described.

FIG. 2 is a diagram showing a vehicle to which the rear wheel steering angle control device for a vehicle according to the embodiment is applied, wherein 1 is a steering wheel, 2 is a steering shaft, 3 is a front steering gear unit,
4,5 are front wheels, 6 is a rear steering cylinder, 7 and 8 are rear wheels, the front wheels 4,5 are steered by the operation of the steering wheel 1, and the rear wheels 7, 8 are hydraulic pressures supplied from the hydraulic pressure source 9. It is steered under the control of.

The vehicle rear wheel steering angle control device for controlling the steering angles of the rear wheels 7 and 8 has a steering angle sensor 10 (steering angle detecting means), a vehicle speed sensor 11 (vehicle speed detecting means), and a yaw rate sensor as input sensors. 12 (vehicle output actual value detection means) is provided,
As an electronic control circuit, a rear wheel steering angle control unit 13 (including an actual steering angle calculation unit, an actual steering angle correction value calculation unit and a final actual steering angle calculation unit) mainly including a microcomputer is provided, and as an output member, A rear wheel steering control valve 14 is provided.

The rear steering cylinder 6, the hydraulic power source 9, and the rear wheel steering control valve 14 constitute an actual steering angle control unit in the claims.

FIG. 3 is a block diagram of the rear wheel steering angle control unit 13, which has a reference model 131 that models desired dynamic characteristics and an estimation model 132 that models the dynamic characteristics of the own vehicle. The vehicle motion target value Yr set based on the steering angle θ and the vehicle speed V is added to the vehicle motion estimated value by the estimation model 132. , The rear wheel steering angle target value δ _R is calculated in order to obtain a response, and the yaw rate (vehicle output actual value) from the yaw rate sensor 12 and the yaw rate estimated value from the estimation model 132 are calculated. Rear wheel steering angle correction value δ _RB by comparison with (vehicle output estimated value)
A rear wheel steering angle correction value calculation unit 13b, a rear wheel steering angle correction value δ _RB, and a rear wheel steering angle target value δ from the rear wheel steering angle calculation unit 13a.
Final rear-wheel steering angle calculation section 13c for calculating the final rear-wheel steering angle target value [delta] _R ^* by the _R is provided.

The vehicle 5 equipped with the vehicle rear wheel steering angle control device according to the embodiment has a front wheel steering angle θ and a final rear wheel steering angle target value δ during steering.
_A predetermined yaw rate is generated under the influence of the rear wheel turning angle according to _R ^* .

 Next, the operation will be described.

First, in the reference model 131, the vehicle motion target value Yr is calculated by the following transfer characteristics.

Here, G (V) is a gain given in advance according to the vehicle speed V, τ is a time constant given in advance, s is a Laplace operator, and θ is a front wheel steering angle.

Next, the estimation model 132 calculates the vehicle motion estimation value of the own vehicle by the calculation based on the following state equation. Ask for.

Where a ₁₁ = -2 (L _F ² K _F + L _R ² K _R ) / Iz ・ (1 / V) a ₁₂ = -2 (L _F K _F −L _R K _R ) / Iz ・ (1 / V) a ₂₁ = -2 (L _F K _F -L _R K _R ) / M ・ (1 / V) -V a ₂₂ = -2 (K _F + K _R ) / M ・ (1 / V) b ₁₁ = 2L _F K _F / Iz ・ N b ₁₂ = −2L _R K _R / Iz b ₂₁ = 2K _F / MN b ₂₂ = 2K _R / M If the above equations are the state equation and the output equation, respectively, Yr ＝ Ar ・ Yr ＋ Br・ Θ… ′ However, Is.

Next, in the rear wheel steering angle calculation unit 13a, the vehicle motion target Yr and the vehicle motion estimated value The rear wheel steering angle target value δ _R is calculated by and.

Where K ₁ = (K ₁₁ K ₁₂ ), K ₂ , K ₃ is However, since e = Yp−Yr or more, And solve the Riccati equation A ₁ ^T P ₁₁ + P ₁₁ A ₁ + Q ₁ −P ₁₁ B ₁ Q ⁻¹ B ₁ ^T P ₁₁ = 0… for P ₁₁ , then A ₁ ^T P ₁₂ + P ₁₁ A ₂ + P By the solution P ₁₂ of ₁₂ A _R −P ₁₁ B ₁ RB ₁ ^T P ₁₂ = 0 ..., (K ₁ K ₂ ) = − R ⁻¹ B ₁ ^T P ₁₁ … K ₃ = −R ⁻¹ B ₁ ^T P _The optimum gain is ₁₂ ... (See JP-A-62-241769).

Next, in the rear wheel steering angle correction value calculation unit 13b, the yaw rate from the yaw rate sensor 12 and the yaw rate estimated value from the estimation model 132 are calculated. By inputting and, the rear wheel steering angle correction value δ _RB is calculated by the following formula.

Where K ₀ is a given gain, However, ai is a real number.

Next, in the final rear wheel steering angle calculation unit 13c, the final rear wheel steering angle target value is calculated by the rear wheel steering angle correction value δ _RB and the rear wheel steering angle target value δ _R from the rear wheel steering angle calculation unit 13a. δ _R ^* is calculated by the following formula.

δ _R ^* = δ _RB + δ _R ... Therefore, as shown in FIG. 4, when the transfer characteristic (solid line) of the estimation model given in advance does not match the transfer characteristic (dotted line) of the vehicle to be controlled, In the rear wheel steering angle correction value calculation unit 13b, the yaw rate estimated value of the estimation model 132 is calculated. The rear wheel steering angle correction value δ _RB is calculated by the above formula based on the difference between the yaw rate and the yaw rate obtained by the detection, and the final rear wheel steering angle calculation unit 13c further calculates the rear wheel steering angle correction value δ _RB and the rear wheel steering angle. The final rear wheel steering angle target value δ _R ^* is calculated by the above-mentioned equation by the rear wheel steering angle target value δ _R from the angle calculation unit 13a.

That is, the yaw rate that is the control result is fed back, and this yaw rate is the yaw rate estimated value. The rear wheel steering angle target value δ _R is corrected so as to match with.

As described above, as shown in FIG. 5, the yaw rate characteristic (solid line) of the reference model that gives the target value of the vehicle motion and the yaw rate characteristic (dotted line) of the vehicle appearing as the control result substantially match, and the vehicle desired at the time of steering can be obtained. A yaw rate characteristic can be obtained.

As described above, in the vehicle rear wheel steering angle control device of the embodiment, a desired vehicle yaw rate characteristic that matches the yaw rate motion target value of the reference model 131 is obtained, and
The following effects can be achieved together.

Unlike the method of increasing the order of the estimation model, there is no calculation complexity associated with the increase in order, so the load on the computer used for control is small, and the calculation step (control cycle) is also small enough not to cause a response delay. You can

Since the yaw rate of the vehicle, which is the control result including all running condition elements such as rainfall and changes in road friction coefficient, is fed back, the rear wheel steering angle target value δ _R is corrected and controlled. Not only when there is a difference between the transfer characteristics of the model 132 and the transfer target vehicle, but also when the transfer characteristics of the vehicle match the transfer characteristics of the estimated model not only when there is rainfall or changes in the road friction coefficient, etc. Have sex.

The embodiment has been described with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the present invention is applicable even if there is addition or change of control without departing from the gist of the present invention. include.

For example, in the embodiment, the device for controlling the steering angle of the rear wheel is shown. However, the present invention is also applicable to a four-wheel steering vehicle that controls the steering angle for both the front and rear wheels.

Further, although the control example of observing the dynamic characteristics of the vehicle by the yaw rate is shown, it is of course possible to use an example of observing the dynamic characteristics of the vehicle by the lateral acceleration, an example of observing the linear combination of the yaw rate and the lateral acceleration, or the like.

(Effects of the Invention) As described above, in the vehicle actual steering angle control device of the present invention, the vehicle output for detecting the vehicle output actual value which is the actual value of the vehicle motion corresponding to the vehicle motion target value. An actual value detection means is provided, and an actual value is output between the actual steering angle calculation section and the actual steering angle control section by comparing the actual vehicle output value from the actual vehicle output value detection means and the estimated vehicle output value from the estimation model. The actual steering angle correction value calculation unit for calculating the steering angle correction value, and the final steering angle target value calculated by the actual steering angle correction value and the actual steering angle target value from the actual steering angle calculation unit are used for the actual steering angle control. Since the final steering angle calculation unit that outputs to the section is provided, even if there is a difference between the transfer characteristics of the estimated model and the transfer characteristics of the vehicle, the calculation load is small and the change in the driving situation does not affect the norm. It is possible to obtain the desired vehicle dynamics that match or follow the target motion value of the model. The effect is obtained.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims showing the vehicle actual steering angle control device of the present invention, FIG. 2 is an overall view showing a vehicle to which the vehicle rear wheel steering angle control device of the embodiment of the present invention is applied, and FIG. FIG. 5 is a block diagram showing a rear wheel steering angle control unit for a vehicle rear wheel steering angle control device according to an embodiment, FIG. 4 is a diagram showing different estimated model transfer characteristics and vehicle transfer characteristics, and FIG. 6 is a comparison diagram of the reference model yaw rate characteristic and the vehicle yaw rate characteristic, FIG. 6 is a diagram showing different estimated model transfer characteristics and vehicle transfer characteristics, and FIG. 7 is a reference model yaw rate characteristic in the conventional apparatus. FIG. 3 is a comparison diagram of a yaw rate characteristic of a vehicle. a: Steering angle detection means b: Vehicle speed detection means c: Actual steering angle calculation section d: Actual steering angle control section e: Reference model f: Estimated model g: Vehicle output actual value detection means h: … Real steering angle correction value calculation unit i …… Final actual steering angle calculation unit

Claims (3)

(57) [Claims] 1. A steering angle detecting means, a vehicle speed detecting means, and an actual steering angle calculating section for inputting signals from the both detecting means and calculating an actual steering angle target value of at least one of front wheels or rear wheels. An actual steering angle control unit that controls the actual steering angle of at least one of the front wheels and the rear wheels corresponding to the actual steering angle calculation unit, and the actual steering angle calculation unit is a reference model that models desired dynamic characteristics. And an estimation model that models the dynamic characteristics of the host vehicle, and obtains a response in which the estimated vehicle motion value of the estimation model matches or follows the vehicle motion target value that is set based on the reference model, the steering angle, and the vehicle speed. In the vehicle actual steering angle control device for which the actual steering angle target value is calculated, vehicle output actual value detection means for detecting the vehicle output actual value which is the actual value of the vehicle motion corresponding to the vehicle motion target value is provided, The actual steering angle calculation unit and the actual steering angle control An actual steering angle correction value calculation unit for calculating an actual steering angle correction value by comparing an actual vehicle output value from the actual vehicle output value detection means and an estimated vehicle output value from the estimation model. The provision of a final actual steering angle calculation unit for outputting the final actual steering angle target value calculated by the actual steering angle correction value and the actual steering angle target value from the actual steering angle calculation unit to the actual steering angle control unit. A characteristic vehicle steering angle control device. 2. The actual steering angle control device for a vehicle according to claim 1, wherein the vehicle output value is a vehicle yaw rate, and the vehicle motion target value and the vehicle motion estimated value are a yaw rate motion target value and a motion estimated value. . Wherein the actual steering angle correcting unit and the final actual steering angle calculating _{^{unit, δ * = δ 0 + δ}} 1 = δ 0 + K ( Contact -M) [delta] ^*; final actual steering angle target value [delta] _0; actual steering angle target value [delta] _1; actual steering angle correction value K; gain; vehicle output estimate M; for a vehicle according to claim 1, wherein a portion to calculate the final actual steering angle target value [delta] ^* by the vehicle output becomes actual relations Actual steering angle control device.